No. Deleting a partition in Gparted just removes some information from the partition table in the MBR. The actual files and folders are still on the hard drive and could be recovered with the appropriate tools.

Quote:

Filling the drive with zeros? Does this remove partitions too?

Yes. It would also erase the partition table. To use the drive again, you would have to build a new partition structure.

A common method used to counter data remanence is to overwrite the storage medium with new data. This is often called wiping or shredding a file or disk. Because such methods can often be implemented in software alone, and may be able to selectively target only part of a medium, it is a popular, low-cost option for some applications. Overwriting is generally an acceptable method of clearing, as long as the media is writable and not damaged.

The simplest overwrite technique writes the same data everywhere—often just a pattern of all zeros. At a minimum, this will prevent the data from being retrieved simply by reading from the medium again using standard system functions.

In an attempt to counter more advanced data recovery techniques, specific overwrite patterns and multiple passes have often been prescribed. These may be generic patterns intended to eradicate any trace signatures, for example, the seven-pass pattern: 0xF6, 0x00, 0xFF, random, 0x00, 0xFF, random; sometimes erroneously attributed to the US standard DOD_5220.22-M.

One challenge with an overwrite is that some areas of the disk may be inaccessible, due to media degradation or other errors. Software overwrite may also be problematic in high-security environments which require stronger controls on data commingling than can be provided by the software in use. The use of advanced storage technologies may also make file-based overwrite ineffective.

Not to start an argument or fight but your quote states that a single "wipe" is all that is required not a single pass, and as this quote shows a single pass using 0's is only effective against standard system functions not specific data recovery methods.
Yes GustavoYz that is why i refered to the tool I posted , you can configure the type of wipe you want to do which ex. three pass wipe, first pass zeros, second pass random character, third pass p character, verification pass. Quite effective for making sure anyone short of a government agency could not recover data from your hard drive.

In Gutmann's original article, he talks about extracting information from an erased hard drive by using techniques like Magnetic Force Microscopy. That means that you have to open the drive, remove the platters and analyse them with specialized equipment and trained technicians.

It's not like someone is going to pull your hard drive out of a dumpster, plug it into his own computer and extract your credit card number.

Even Gutmann has now backed away from his original erasure method because hard drive technology has changed so much in the interim.

Consider this scenario. You use dd to fill the drive with zeros using a single pass. You then read it back using dd and get nothing but zeros. You read it again and still get zeros. Why would you expect that someone else reading the drive would get the original data?